Unmanned, electrically driven small aircraft with typical weights of approximately 10 kg or less are being used for monitoring and information in the lower altitude range of approximately 5 km to 10 km flying altitude. When such small aircraft are used, the goal may be, for example, to maximize the use time and/or flight time and to impart a speed and stability to the aircraft that will make it possible to maneuver them freely for most of the flight time and/or use time against prevailing winds and turbulence in the atmosphere and even rain. The aircraft must therefore have adequate mechanical strength, a sufficiently high surface load and a sufficiently high driving power. These requirements can result in an increase in the weight of the aircraft, such that power obtained from regenerative power sources on board the aircraft may not be sufficient under some circumstances to operate such an aircraft over a period of time of several days, for example, without interruption, i.e., to keep it in the air. Providing power storage devices in the form of batteries can run counter to this goal under some circumstances because such power storage devices bring a certain amount of inherent weight, so they may further increase the total weight of the aircraft, which can in turn increase the power demand.
DE 10 2011 010 679 A1 describes a design and a control system of an unmanned aircraft, in which power is supplied to drive the aircraft by on-board power storage devices.